1. Technical Field
The disclosure relates to a rotational kinetic energy output device and more particularly to a thin rotational kinetic energy output device.
2. Related Art
There are many types of motors, if categorized by directions of magnetic flux, and they are divided into axial magnetic flux motor, radial magnetic flux motor and motor having magnetic flux changed from axial to radial (such as claw pole motor). Furthermore, the stators of motors are divided into a few types in terms of structure and application: iron core is structured in one body, structure having independent iron cores, or various coreless or slotless structures.
For a motor stator which has an iron core, the stator is manufactured by stamping magneto-conductive plates to fit the iron core shape, having the plates piled together into layers to form the iron core, and afterwards, having the iron core wound with coils. However, materials are wasted substantially if the abovementioned method is applied in manufacturing a stator of an internal-rotor motor. The larger the power of a motor is, the more materials are wasted in a manufacturing process of iron core, especially for radial magnetic flux motor.
As products are getting more compact and thinner, motor is also required to be developed with thinner design. Typically, axial magnetic flux is mainly applied in motor with thin and compact design. Axial magnetic flux motor can be divided into three types in terms of configuration of rotor and stator, which are single stator and single rotor, dual stator and single rotor as well as dual rotor and single stator.
Motor with single stator and single rotor is the best for meeting the requirements of thinness and compactness. However, a bearing of a motor with a single stator and a single rotor is easily worn out because a force is unevenly exerted on the rotor, which increases the cost of bearings.
If a motor with dual rotor and single stator, or with dual stator and single rotor is employed, besides that a force is evenly exerted on the rotor and therefore, the bearing life is extended, a power or a torque density of the motor can be enhanced as well. However, the motor will be large in size which is a drawback for the requirement of thin and compact design.